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<p>
    Executes the stage if the current build is for a change request
    <em>(a.k.a. <strong>Pull Request</strong> on GitHub and Bitbucket, <strong>Merge Request</strong> on GitLab or <strong>Change</strong> in Gerrit etc.)</em>.
</p>
<p>
    Similar as for <code>branch</code> and <code>tag</code> it checks the values of the <code>CHANGE_*</code> environment variables set by the branch-api plugin,
    you can check the values of those via individual parameters. If more than one parameter is specified, then all of the parameters must match.
</p>
<p>
    Using no parameters i.e. <code>when { changeRequest() }</code> it will just check that <code>CHANGE_ID</code> is available and has a value.
</p>

